1. Field of the Invention
The present invention relates to an improvement on a cartridge chamber cover locking device arranged to be capable of switching the state of a cover of a film cartridge chamber of a camera between an unlocked state in which the film cartridge chamber can be opened and a locked state in which the film cartridge chamber is kept closed.
2. Description of Related Art
A film cartridge of the so-called thrust type having a film stowed in a completely wound state therein including its leader part (hereinafter referred to simply as a cartridge) has become known during recent years. A camera adapted for the cartridge of this type is arranged to cause the film to be moved out from the cartridge by a film transport mechanism disposed within the camera and to take up and wind the film on a spool shaft of the camera when the camera is loaded with the cartridge. The camera of this kind permits the cartridge to be put into and taken out from a cartridge chamber in the axial direction of a supply spool of the cartridge. Therefore, the cover of the cartridge chamber can be disposed either on the upper or lower side of the camera body.
Further, the camera of this kind is arranged to set an indication of the usage state of the film, after completion of rewinding the film, by using an index which rotates integrally with the supply spool of the thrust-type cartridge and one of indication marks provided on the cartridge case for indicating unexposed, partially-exposed, completely-exposed and developed states of the film. In other words, the indication of the usage state of the film is set by adjusting the position of the index to that of an applicable indication mark.
However, the camera of this kind has presented the following problem. If the user attempts to forcibly take out the cartridge by opening the cover of the cartridge chamber while the film is in a state of being pulled out of the cartridge, there is a possibility that the film is not only exposed to light but also is broken or left inside of the camera body in a broken state. In the event of such an accident, the camera must be sent for a repair as the film cannot be easily taken out from the camera by the user.
Further, in the case of the camera arranged to be capable of setting an indication showing the usage state of the film, if the cartridge is taken out by opening the cover of the cartridge chamber before completion of the process of adjusting the index to the position of an applicable indication mark, it would become impossible to correctly position the index and, after that, the usage state of the cartridge would become undiscernible.
Further, if an actuator is used solely for operating a lock mechanism of the cartridge chamber cover, the use of the actuator increases the size and cost of the camera.
A device disclosed in Japanese Laid-Open Patent Application No. Hei 6-258699 (corresponding to U.S. Pat. No. 5,432,575) is arranged to lock and unlock the cover of a cartridge chamber by using a part of a stowage area provided in a camera body for stowing a photo-taking lens barrel. According to such an arrangement, however, the area provided for stowing the photo-taking lens barrel becomes smaller. The small stowage area tends to overload a driving action on the photo-taking lens barrel or, if the photo-taking lens barrel is in a drawn-out state while the camera is not loaded with the cartridge, the photo-taking lens barrel must be drawn inward into the stowage area before loading the cartridge into the camera, because loading the cartridge in that state is impossible. Therefore, the operability of the camera has been greatly degraded by such a small stowage area.
It is a first object of the invention to provide a cartridge chamber cover locking device, or a camera, having two lock means arranged to be capable of reliably preventing the cover of a cartridge chamber from opening while the film of a cartridge is in a state of being pulled out of the cartridge or from being inadvertently opened before the position of an index provided on the cartridge is set at a correct position.
It is a second object of the invention to provide a cartridge chamber cover locking device arranged to permit reduction in cost by obviating the necessity of having a drive source solely for unlocking the cover of a cartridge chamber.
It is a third object of the invention to provide a cartridge chamber cover locking device arranged to be capable of preventing a film from being damaged by an inadvertent opening operation on the cover of a cartridge chamber while the film is in a state of being pulled out of a cartridge.
It is a fourth object of the invention to provide a cartridge chamber cover locking device arranged to obviate the necessity of doing a troublesome operation of unlocking the cover of a cartridge chamber every time a cartridge is to be loaded in the cartridge chamber.
It is a fifth object of the invention to provide a cartridge chamber cover locking device arranged to prevent an increase in size of a camera by effectively utilizing a dead space existing within the camera.
To attain the above objects, in accordance with an aspect of the invention, there is provided a cartridge chamber cover locking device, comprising an operation member for opening a cover of a film cartridge chamber, a first lock member arranged to take, when the cover is in a closed state, one of a locking state of locking the cover against an opening operation performed on the operation member and an unlocking state of unlocking the cover, film transport means for transporting a film, wherein the first lock member takes one of the locking state and the unlocking state in association with a film transporting action of the film transport means, a second lock member arranged to take, when the cover is in a closed state, one of a locking state of locking the cover against an opening operation performed on the operation member and an unlocking state of unlocking the cover, and a lens barrel arranged to be movable forward or backward along an optical axis and to hold an objective lens, wherein the second lock member takes one of the locking state and the unlocking state in association with the movement of the lens barrel along the optical axis.
In the cartridge chamber cover locking device, in particular, the first lock member takes the locking state in association with a film feeding action of the film transport means.
Further, in the cartridge chamber cover locking device, the first lock member takes the unlocking state in association with a film rewinding action of the film transport means.
Further, in the cartridge chamber cover locking device, the second lock member takes the locking state in association with the lens barrel being drawn out forward, and takes the unlocking state in association with the lens barrel coming into a stowed state.
In accordance with another aspect of the invention, there is provided a cartridge chamber cover locking device, comprising an operation member for opening a cover of a film cartridge chamber, a lock member arranged to take, when the cover is in a closed state, one of a locking state of locking the cover against an opening operation performed on the operation member and an unlocking state of unlocking the cover, and a lens barrel arranged to be movable forward and backward along an optical axis and to hold an objective lens, wherein, if a film cartridge is loaded in the film cartridge chamber, the lock member takes one of the locking state and the unlocking state in association with the movement of the lens barrel, and, if no film cartridge is loaded in the film cartridge chamber, the lock member is kept into the unlocking state.
Further, in the cartridge chamber cover locking device, if a film cartridge is loaded in the film cartridge chamber, the lock member takes the locking state when the lens barrel is located in a forward position, and takes the unlocking state when the lens barrel is located in a backward position.
In accordance with a further aspect of the invention, there is provided a cartridge chamber cover locking device, comprising an operation member for opening a cover of a film cartridge chamber, a lock member arranged to take, when the cover is in a closed state, one of a locking state of locking the cover against an opening operation performed on the operation member and an unlocking state of unlocking the cover, film transport means for transporting a film, wherein the lock member takes the locking state in association with a film transporting action of the film transport means, and a lens barrel arranged to be movable forward or backward along an optical axis and to hold an objective lens, wherein the lock member takes the unlocking state in association with the movement of the lens barrel along the optical axis.
In the cartridge chamber cover locking device, in particular, the lock member changes from the locking state to the unlocking state in association with the backward movement of the lens barrel.
These and further objects and features of the invention will become apparent from the following detailed description of preferred embodiments thereof taken in connection with the accompanying drawings.